Graybeard Outdoors banner

357AR (Max-Rimless)

54K views 85 replies 22 participants last post by  moleman 
#1 ·
I've had several people Pm me about the rimless 357Max AR15s I've made so I figured I could add some more info about it. Don't know if removing the rim counts as a wildcatting or not but overall it is a little more detailed so here goes.
5 years back or so I was wanting a better performing/with mild recoil and cheaper alternative to what was available to chamber an ar15 barrel in. The cartridge needed to be a straightwalled case and be less than 1.8" in length for hunting regs. I had previously made a DI (gas operated) 9mm luger ar15 upper and had looked at a 357mag rimless, then thought what about a 357Max rimless. Searching the web I could find lots of other guys who said it couldn't be done and others that had made up dummy rounds but couldn't find anyone who had gone ahead and chambered an upper in it. I've always been told that anything you can think of with wildcatting has already been done and that seems to be the case. So here is what I did to make it work, hopefully it will help others.

The reamer needs to cut a shoulder for the case to headspace on since it no longer has a rim. Looking at 357Max chamber drawings and reamer prints I came up with an initial chamber drawing. I had never made a reamer before, but have three lathes and a bench mill. From the drawing a piece of O1 drill rod was turned around .0015" over final diameter and then polished down to size. 6 Flutes were then laid out .005" below centerline of the reamer blank and then milled out. The blank was heated bright red while being held in a long extension spinning slowly in a drill press. Then dunked in oil while still spinning until cool enough to touch. The reamer is then held between centers and using a boring bar as a guide the flutes are carefully stoned with a diamond hone on a stick. My first reamer wouldn't cut as it was still too soft, so I made another one which worked well.

Not knowing if I'd be able to get it to feed well or not I used a cheap $35 timberwolf blank as a test barrel. Once it was rough turned and an extension installed the feed ramps were modified until they would feed the cylindrical rounds. Which brought me into the next issue. All ar15 mags have bullet feed guides in them to push the shoulder of the cartridge towards the center of the mag as they are pushed forward. The feed guides prevent the straight 357 rounds from double stacking. USGI type mags have them pressed into the metal and they cannot be easily removed. Pmags on the other hand have the feed guides molded in and can be removed with a dremmel and a sanding drum.

Using Quickload as a guide, loads were worked up from reloading manuals until they were at max for standard 357Max loads with 2400 powder, then loads for TC before working up to what QL said would be maximum loads if allowing 223/5.56 pressures of 60k psi. I never shot that barrel for accuracy, just load development and to see if it would cycle the action. Since it did a .358" 1:14" GMB barrel blank was ordered and another reamer was made since the pilot from the first one would be too small. Not to bore you with all of the details, the barrel and second reamer worked out just fine. I continued to work up loads from reloading books using QL as a guide. So far I have loaded 140, 158, 180, 200, 205, and 220gr bullets using bluedot, 2400, and W296. I plan on using other powders and bullets as time allows. My son and I have both harvested deer with our 357AR rifles and have been very pleased with them. The recoil is clearly more than an ar15, but less than my marlin 30-30.


Here's some pics.
 

Attachments

See less See more
8
#2 ·
After Making the my first two barrels I wanted to make a few changes to the reamer, so I had Manson reamers make a reamer in 2012. I was unable to hunt in 2012, but used a pistol chambered with the Manson reamer in 2013. After using that reamer I wanted a little bit less chamber taper, and a little more freebore since the COL can be a lot longer using rifle magazines. Manson had suggested .005" body taper to ease feeding in the auto rifle. My first reamer had .001" taper and did feed, as did my second reamer with .002" body taper. I found that the larger the taper the more quickly the cases needed trimmed. The increased ID was getting traded for increased length when ran through a standard 357max sizing die. Ideally a new tapered sizing would be made, but that takes away from using a readily available carbide die set. So I made yet another reamer only with a floating pilot so it could be used on 357 or 358 barrel blanks with only .003" taper and increased freebore so bullets could be seated out farther and stubby bullets didn't have to be seated deeper to not touch the rifling. That last reamer seems good for what I'm doing so the Manson reamer will eventually get sent back to be updated.
 

Attachments

#3 ·
Cases. Forming the cases is the biggest hurdle. One guy I know uses standard 357Max cases and just removes the rim. Max cases are more expensive than 223/556 once fired cases so that is what I use. It would be very helpful if anyone knows where to get 222 or 223 basic (straight) brass. So far every place I've contacted is unwilling to sell brass off of the line for liability reasons. I understand that, but it is also frustrating knowing that every 223 case at one point is an almost perfect 357AR case that just needs trimmed and reamed. Here is what I've found to be the best way so far to change 223 brass to 357AR brass will acceptable case losses.


1. Decap, trim to 1.640"-1.650" and debur

2. anneal

3. lube inside the case and expand case mouth with skinny expander

4. expand case body with blunt expander

5. resize

6. roll case shoulder wrinkle away (optional)

7. turn necks/ream to .0105" case wall thickness

8. trim to final length 1.595" and tumble

9. load/shoot


This method seems to work very well as I had no split cases out of the 40 or so I formed recently. Usually I've had 5-10 split out of 100 when using once? fired range mystery brass without trimming first. Any flaw in the case mouth of the parent case will result in a split, so the initial trim and debur really cuts down on losses. This batch of LC-13 cases probably would of been fine without turning/reaming, but I've had others like FC cases that wouldn't chamber without turning so I just turn them all. Really all you're reaming or turning off is where the base of the bullet would be.
 

Attachments

#4 ·
Here's the reamer prints from Manson, and the one I've settled on being best for how I'm loading. The headspace gauges I originally made and have chambered my barrels with differ from Mansons specs. I asked Dave Manson about the difference and he basically said it was a choice and as long as you trimmed your brass accordingly either was acceptable.
 

Attachments

#5 ·
AWESOME! Thank you for posting!!

CW
 
#6 ·
So far I've only run across two bullets that have not fed well at all. A long discontinued Hornady 158gr SJHP that the soft lead tips would snag on the barrel extension, and oddly the 140gr FlexTips. I figured the flex tips would feed decent, but every one so far jams. I'll play around with the COL to see if that helps as it has with other bullets. I noticed early on the 158gr XTP fed smoother than the 180gr xtp even though they have the same profile. Basically what was happening is the longer stubby length was wedging on the top of the chamber while still being held by the magazine feed lips. Shortening the COL let the bases clear the magazine feed lips before the fronts were pushed up enough to strike the chamber mouth. I suspect the same thing is happening with the 140flex tips. Oddly I have also shot a 215gr lead GC bullet and the bullet tips got a little dinged up going through the feed ramps, but they shot just fine. Many of the groups I've shot with them have several touching and some that don't. I think with a little effort the group size can be cut down some. The best feeding and shooting one so far has been the now discontinued hornady 180gr SSP which is what we've used on deer so far.
 

Attachments

#7 ·
cwlongshot said:
AWESOME! Thank you for posting!!

CW
Thanks, it's been fun working on this. Couple of rifle/deer pics. Mine is the black one with an 18" barrel and my sons is tan with a 16" barrel. Shot my deer at 50-60yds and he got his at around 110yds. His ended up being over a pound lighter than mine and you can really feed the difference carrying both.
 

Attachments

#9 ·
Since these cartridges are getting shot in a rifle action and were made with cases that started out designed for 60k psi they are capable of being loaded hotter than what's in the books for 357Max. The rifles will cycle with 357Max level cartridges and don't have to be loaded any hotter. We're all adults and shouldn't take any load data provided by someone on the internet as gospel. These loads were slowly worked up from 357Max data listed in a reloading book until at max loading, then worked up further using QuickLoad as a Guide. While safe in my gun they may not be in yours. These are not the top loads I've tried as they generally didn't group as well as lighter loads. Past 50k psi little changes in powder charges and seating depth start having a bigger effect on pressure. There is also a diminishing return exchanging pressure for FPS. I have only used CCI small rifle primer so far. If the Mods think this is inappropriate I will remove them.

While I started off using 2400 these loads are more recent with W296. The 215gr Lead Gas Check bullet was sent to me from a member on another site to try. I was skeptical but tried them and was pleasantly surprised. They were cast from a NOE copy of a RCBS mold http://noebulletmolds.com/NV/product_info.php?cPath=35&products_id=358 . Apparently Lee now makes it in a 2 and 6 cavity. As received they weighed 215 gr.

The 180gr SSP feeds smoother than the other rounds and also shoots great. I did have to make a new top punch for the seating die to stop it from squishing the lead tips. I have loaded the SSP to over 2200FPS in my 18" rifle, but accuracy and case life suffered. The 24gr load is what I used in my rifle and the 23gr load is what my son shot out of his.
 

Attachments

#10 ·
Congrats, I knew someone would get around to a 35 cal AR based on 5.56 cases.

I have a DW revolver and a TC Contender 10" barrel in 357 max.


Just to confirm it would work, I found that I could fire "rimless max" ammo made from 5.56 cases using a Contender 222 extractor for headspacing.


Expanding / fireforming to get full length cases was a real pain.


On the flip side, with the pressures available in a AR or other rifle, are full length Max cases really worth it?


A 5.56 trimmed at the base of the shoulder would give you a case length of say 1.43". Compare to:


- 357 Mag: 1.29"
- DW 360: 1.41"
- 357 Max: 1.605"


If you shoot cast, it would be pretty easy to get the same cartridge OAL since the std Max has lots of bullet shank inside the case.


If you shoot Jacketed, the factory crimp groove on most bullets would not be optimum, but the combination of an extra 0.14" (compared to a mag) and the extra pressure available would give you as good as or better performance as folks that have use DW 360s in rifles originally sold as 357 magnums.


If you are building a custom AR, starting off with a chamber for 1.43" brass (or 1.41" and calling it a rimless DW 360) would allow you to try out an "cheap & easy brass" solution first.


If you just can not get enough performance, going the extra depth would be still be available using the same reamer and just taking it deeper.


FYI, my rimless experiment was conducted at a time when I was short on max cases, and I could find no "new production" stuff on the market. I also tried some at longer than max to get my cast bullets out far enough to seat in the riling (I got better ignition).


Later I fixed my brass shortage with 200 Jamison cases.


If I ever run into anyone else with a Contender max and with no access to factor maximum or factory DW 360 cases, I would recommend that they try out the 'rimless DW 360" solution until they can find real maximum or DW 360 cases. With either real DW 360 cases or with "rimless DW 360" cases, you can load to any pressure your gun is rated for without worry that your loads could accidentally wind up being fired in a lightweight 357 magnum revolver.
 

Attachments

#11 ·
Sounds neat P Flados, I had looked at 357Auto (223-ar15) and 360DW but went with the Max case so generally I'd have at least one caliber inside the case to be better supported for cycling through the action if they were loaded to a longer COL to fit inside of an ar15 mag. Here's some 180gr ssp in a modified Pmag. They just fit and still have .350" inside of the case. I initially tried just fireforming 223 cases straight with wax bullets and red dot. It took several firings to get where the two expanders do without firing a shot. It still takes one firing with a 357max level loading to fully iron out the case before jumping up the pressure level. One of the first cases made was fired 12x in the tight .001" chamber before it needed trimmed. The cases fired in the other chambers with more taper need trimmed quicker. I've got a pic somewhere of a case fired at least 12x that was sectioned somewhere I'll put up when I find it.
 

Attachments

#12 ·
What 220g bullets have you tried?


Any Kieth style by chance? I would think they likely problematic...


I tried these last year in the maxi. They shot well, but effect powder cap too much for good velocity.





They are over 230 after GC & lube.


CW
 
#13 ·
I haven't tried any other lead bullets besides the ones posted earlier that had a slight ogive to them. I'm going to guess they may catch, but there's no way to tell for sure until some get loaded up and tweaked for COL to see if they'll feed. I didn't think the 215gr lead bullets that KLR on another site sent me would feed at all, but was surprised enough on how well they worked that I will be ordering that mold as they will make for some cheap plinking. The 200gr were Sierra RN and the 220's were a partial box of Speer #2439 that someone had sent me to try. I haven't shot either one of these with W296 yet, but it looks like at least with the 200gr Sierra another 100fps can be gained from switching to W296
 

Attachments

#15 ·
If you would like to try some, PM me a address I'll send a handful.


CW
 
#17 ·
Moleman said:
Since these cartridges are getting shot in a rifle action and were made with cases that started out designed for 60k psi they are capable of being loaded hotter than what's in the books for 357Max. The rifles will cycle with 357Max level cartridges and don't have to be loaded any hotter. We're all adults and shouldn't take any load data provided by someone on the internet as gospel. These loads were slowly worked up from 357Max data listed in a reloading book until at max loading, then worked up further using QuickLoad as a Guide. While safe in my gun they may not be in yours. These are not the top loads I've tried as they generally didn't group as well as lighter loads. Past 50k psi little changes in powder charges and seating depth start having a bigger effect on pressure. There is also a diminishing return exchanging pressure for FPS. I have only used CCI small rifle primer so far. If the Mods think this is inappropriate I will remove them.

While I started off using 2400 these loads are more recent with W296. The 215gr Lead Gas Check bullet was sent to me from a member on another site to try. I was skeptical but tried them and was pleasantly surprised. They were cast from a NOE copy of a RCBS mold http://noebulletmolds.com/NV/product_info.php?cPath=35&products_id=358 . Apparently Lee now makes it in a 2 and 6 cavity. As received they weighed 215 gr.

The 180gr SSP feeds smoother than the other rounds and also shoots great. I did have to make a new top punch for the seating die to stop it from squishing the lead tips. I have loaded the SSP to over 2200FPS in my 18" rifle, but accuracy and case life suffered. The 24gr load is what I used in my rifle and the 23gr load is what my son shot out of his.
Being a Hoosier, this is cool as all get out!!
 
#19 ·
omegahunter said:
Being a Hoosier, this is cool as all get out!!
Thanks! We actually started looking at it for use by my son in WI, MO, or Northern Michigan since we're in limited firearms zone (shotgun) here in southern MI. Previously we had planned on him using my 6x45 since it has little recoil. I think this is a better solution. I hunted with the pistol in 2013, then in 2014 the DNR allowed pistol caliber rifles in the limited zone so I happily used mine. Unless some manufacturer grabs the concept and runs with it, I doubt it will take off as there is no commercially available ammo. We usually do get questions about what it is when we go to the range and shoot so there is at least some interest.
 
#21 ·
I agree, this is very cool. It would be a good option here in Ohio. If you ever need some additional testing just let me know.

Jim
 
#22 ·
Here's a couple pics of my sons rifle being made. Standard lower, upper bolt, carrier, handguard, gas tube, gas block, ar10 A2 flash hider, modified Pmag, modified barrel extension. Turned from a Green Mountain .358" 1:14" blank. Parkerized then covered in gunkote. I seem to be missing a bunch of pics of the turning, threading ect. If they're not hiding on another SD card somewhere I'll take some more to add next time I'm making a barrel.
 

Attachments

#24 ·
Mikey said:
Moleman: did you consider the 9mm magnum case when thinking up your cartridge? I don't think it is as long as the 357 max but it is rimless.
I hadn't really looked at the 9mm magnum although it was brought up along with most every thing else similar when I was first looking at building something. There is a much better heavy bullet selection in .357"-.358" than in .355". As long as the bullets fit behind the bullet guides in the magazines so that they can still double stack you'd be able to use just about any type of mag. Really since I'm using this as a hunting tool being limited to a few types of poly mags isn't a big issue. I'm tempted to try and make my own steel mag body to see if I can get standard 357Max ammo to feed. Headspacing the rimmed case would just be a minor inconvience then, but would be more than made up for by using off the shelf brass.
 
#25 ·
The 9 MM Mag is a 1.160 case compaired to 1.610 for the Maxi, so almost 1/2" shorter.

But the base dia is .391 compaired to .376 and .379 for the 223/Maxi. So too big at the base.

Not a option for this chamber, but might be for a different build, of coarse the brass is scarce as well.

CW
 
  • Like
Reactions: 7.62 Nato
#26 ·
A 9mm mag might allow you to use a standard 9x19 barrel that is rechambered to 9m mag and only have to thread the barrel for the extension and set the FSB journal back 1/2" or so. There is a lot of lathe time turning down a 1.25" blank. The max case still has quite a bit more case volume. I had thought about using another case for slightly more volume but then you run into readily available dies/data ect.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top